Product and method and composition for cadmium-tin alloy plating



Patented Sept. 14, 193'? Q I UNITED STATES; PATENT OFFICE Leroy Camel, Maple Heights, Ohio, assign'or to The Plating and Galvanizing Company, Cleveland, Ohio, a corporation of Ohio No Drawing, Application Apr-ill, 1937,

Serial No. 134,425

6 Claims.- (Cl. 204-1) This invention, as indicated, relates to a meth solution in the form' of various compounds of od and composition for cadmium-tin alloy platsuch element, or as a portion of the anode; ing, especially in relation to ferrous articles. The preferred formula for-producing the elec- More particularly, it comprises a composition trolyte comprises the following:

having a combination of elements adapted to 5 5 bring about bright plating of cadmium-tin alloy, gggm f ggfi j Per 9 "gg g 7 resulting in a new product, and providing .a Tin oxide "5"";31'32; E;- 02 methodadaptable for quantity production with 'f g I Glue (.88 oz.) cc. per gal. of water 25 a productof uniform quality and dependable iln- Sodium h droxide oz er I f t r 10 ish. The invention especially includes the plat-, Water y w s- 1 10 ing of ferrous articles with an alloy of cadmium Z s and tin, the tin'being present in relatively small As has been stated, some latitude of proporamount, but being effective in conjunction with tions is permissible, as well as certain substituthe other elements employed in producing a tion of equivalents, but the amount of tin oxide bright cadmium-tin alloy coating comparable or other source of tin for the electrolyte must be 16 with platings produced through the use of spekept closely to the lower limits, inasmuch as an cial brightening agents which are not alloyed. excess of tin results in a deposit of a spongy Various types of cadmium plating composicharacter which cannot be maintained under setions and processes are known, but many of these vere conditions of use and which will not be of a 20 are not adapted for commercial use either bebright finish. When the amount of tin is kept 20 cause of cost or intricacy of handling, or by at approximately the amount stated in the forreason of difliculty in maintaining uniformity of mula above set forth, the resulting plating is not product. Heretofore the use of tin and elements only as bright as can be obtained through the use associated with the tin group have been referred of various brightening agents, such as sulnto as having a detrimental effect in the cadmium phonated 11 and th like, t is of a more t bath, tin bei d s b as "analogous to the cious character, and corrosion effects on the poisoni e e of arsenic in other catalytic coating are avoided for a much longer period. Operations? If desired, a mixture in dry form of all the The present invention utilizes a cyanide bath ingredients, including the glue in granulated as the electrolyte and includes the same, form may be prepared in a single package and 30 small quantities Of compounds to improve the upon the addition of such ingredients to a water conductivity Of the bath and to bring about a bath, which may be very moderately heated t bright coating upon the articles being plated' assist in the speed of dissolution of the powdered It has been found that the cyanide bath in genand granular material the h Wm be ready era] results in the best quality of color for the for use. v product, but in many instances the time factor The bath, when fully prepared Wm be found of the ODeFa'tiOn has 5 23 or ifi s i of to permit the use of current up to 45 amperes in the operatlon has been d c W 8 the plating circuit,or as low as 10. amperes per position herein described, it has been found that 40 a uniformly high rate of production can be main- 33 foot of surface at preferably from 3 to 5 40 tained and a durable coating of a cadmium-tin The anode utilized preferably comprises a comauoy deposit of high lustre can be maintained on position of pure cadmium and tin in the relative the product, with no unfavorable factors to be g taken into account as to the maintenance of the g i whicg W P f bath bath or excessive cost or complication in carrying pare m accor W1 e 0mm However 45 out the process an anode of pure cadmium may be utilized with the tin present in the solution, or an anode par- The process, while adapted to be carried out in certain proportionate relations between the many formed of cadmium with or without tin elements entering into the same, is by no means assoclated therewith, and may be utilized with restricted to certain critical proportions, but has non'metanlc anodes- 50 a reasonable range of limits as to quantities, as A1? a temperature between 60 and 0 de ree well as to substitution of equivalent elements. Fahrenheit, the Plating bath above Set forth will t is pointed t, h w t t t amount of coat ferrous articles with a smooth tenacious tin used must be maintained at a very small coating of cadmium-tin alloy in approximately amount, whether the tin is introduced into the from 4 to 6 minutes, and such coating will be of 56 durability and resistance to corrosion.

When articles are plated with the cadmium-tin alloy as above outlined, they may be used for many purposes without any finishing treatment, such as buffing or the like. The coating referred to is also adapted to form a base coating upon which some other metals, such as nickel or chrome, may be deposited with an unusuall bright and hard finished effect. 1

Other modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the means and steps herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. The process of producing bright smooth coatings of cadmium-tin alloy on ferrous articles, which includes the step of adding to a cyanide electrolytic bath in addition to thecadmium an amount of tin not in excess of 0.2 grams per gal-' ion of electrolyte to serve as an alloy with the cadmium.

2. The process of cadmium-tin alloy plating in a cyanide bath which comprises the electroplating of cadmium with an amount of tin associated therewith, the cadmium being in the form of an oxide in the proportion of 5 ounces per gallon of water, and the tin being in the form of an oxide in the proportion of 0.2 grams per gallon of water.

fine grain and bright texture, and have great 3. The process of cadmium-tin alloy plating which comprises the electroplating of cadmium from a cyanide bath containing cadmium oxide, and tin oxide in concentration in the order of 0.2 grams to the gallon in the presence of sodium hydroxide, and animal glue as a colloidal brightening agent.

4. In a cadmium tin cyanide bath for electroplating, the combination of sodium cyanide to the amount of 16 ounces per gallon of water, cadmium oxide to the amount of 5 ounces per gallon of water, tin oxide to the amount of 0.2 grams per gallon of water, glue to the amount of 25 cubic centimeters per gallon of water, and sodium hydroxide to the amount of 3 ounces per galion, of water.

5. A composition of matter adapted for use in forming an electrolyte for the electrodeposition of a cadmium-tin alloy on ferrous articles, consisting for each gallon of water to be used of dry pulverized and granular material in the proportion of 16 ounces of sodium cyanide, 5 ounces of cadmium oxide, 0.2 grams of tin oxide, .88 ounces of glue, and 3 ounces of sodium hydroxide.

6. As a new article of manufacture, a metal article having an electrolytic coating comprising an alloy of cadmium and tin produced by the process of electrodepositing said coating from a cadmium cyanide electrolytic bath containing in addition to the cadmium oxide an amount of tin oxide not in excess of 0.2 grams per gallon of electrolyte to serve as an alloy with the cadmium.

LEROY CAMEL-' 

